Worksheet: Converting Concentrations to pH and pOH

In this worksheet, we will practice converting between hydronium and hydroxide ion concentrations in water and the corresponding values of pH and pOH.

Q1:

The hydronium ion concentration of vinegar is approximately 4 . 0 × 1 0 3 M. What is the corresponding value of the pOH?

  • A 4 × 1 0 3
  • B2.4
  • C1.0
  • D12
  • E13

Q2:

What is the pH of a 0.0125 M solution of potassium hydroxide, K O H ?

  • A0.0125
  • B1.90
  • C9.99
  • D12.1
  • E4.01

Q3:

What is the pOH of a 0.0125 M solution of potassium hydroxide, K O H ?

  • A0.0125
  • B12.1
  • C9.99
  • D1.90
  • E4.01

Q4:

To 1 decimal place, what is the pH of 0 . 2 1 M N a O H at 2 5 C ? Assume that N a O H ionizes completely.

Q5:

To 2 decimal places, what is the pH of 0 . 0 0 0 0 7 1 M B a ( O H ) 2 at 2 5 C ? Assume that B a ( O H ) 2 ionises completely.

  • A9.85
  • B3.85
  • C4.15
  • D10.15
  • E11.20

Q6:

To 2 decimal places, what is the pOH of 0 . 2 1 M N a O H at 2 5 C ? Assume that N a O H ionizes completely.

Q7:

To 2 decimal places, what is the pOH of 2 . 5 M K O H at 2 5 C ? Assume that K O H ionizes completely.

Q8:

To 1 decimal place, what is the pH of 2 . 5 M K O H at 2 5 C ? Assume that K O H ionizes completely.

Q9:

To 2 decimal places, what is the pOH of 0 . 0 0 0 0 7 1 M B a ( O H ) 2 at 2 5 C ? Assume that B a ( O H ) 2 ionizes completely.

Q10:

Calculate to 3 significant figures the hydroxide concentration of a solution with a pH of 6.52 at 2 5 C . The self-ionization constant of water, 𝐾 w , is 1 . 0 0 × 1 0 1 4 at this temperature.

  • A 5 . 0 6 × 1 0 7 M
  • B 3 . 0 1 × 1 0 7 M
  • C 6 . 7 9 × 1 0 9 M
  • D 3 . 3 1 × 1 0 8 M
  • E 8 . 9 5 × 1 0 9 M

Q11:

Coffee has a pH of about 5.1. Calculate to 2 significant figures the hydroxide ion concentration of coffee at 2 5 C .

  • A 6 . 3 × 1 0 1 1 M
  • B 7 . 9 × 1 0 6 M
  • C 1 . 6 × 1 0 1 8 M
  • D 1 . 3 × 1 0 9 M
  • E 1 . 2 × 1 0 1 2 M

Q12:

To 2 decimal places, what is the pH of 0 . 0 1 4 3 M N a O H at 2 5 C ? Assume that N a O H ionizes completely.

Q13:

To 1 decimal place, what is the pOH of 3 . 0 M H N O 3 at 2 5 C ? Assume that H N O 3 ionizes completely.

Q14:

To 2 decimal places, what is the pOH of 0 . 0 1 4 3 M N a O H at 2 5 C ? Assume that N a O H ionizes completely.

Q15:

What is the pOH of 0 . 0 0 3 1 M C a ( O H ) 2 at 2 5 C ? Assume that C a ( O H ) 2 ionizes completely.

  • A2.5
  • B11.8
  • C11.5
  • D2.2
  • E1.7

Q16:

To 1 decimal place, what is the pH of 0 . 0 0 3 1 M C a ( O H ) 2 at 2 5 C ? Assume that C a ( O H ) 2 ionizes completely.

Q17:

The p O H of the conjugate base of an unknown aqueous acid is 4.17. What is the H + concentration of the unknown acid?

  • A 6 . 7 6 × 1 0 5 M
  • B 2 . 2 7 × 1 0 1 2 M
  • C 4 . 6 6 × 1 0 2 M
  • D 1 . 4 8 × 1 0 1 0 M

Q18:

To 1 decimal place, what is the pOH of a 0.000259 M aqueous H C l O 4 solution at 2 5 C ? Assume that H C l O 4 is completely ionized.

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